Re: [RFC, experimental] save_{excursion,restriction}

[Dmitry Antipov]

On 07/24/2012 01:37 PM, Stefan Monnier wrote:

> BTW, why use an extra `excursions' field rather than just use a new
> Lisp_Object type for "struct excursion"?
> I think that would be cleaner to either make them into
> Lisp_Pseudovector or Lisp_Misc.

1) "excursion state" is not visible to Lisp programs and so not referenced
via Lisp_Objects, it's just a service thing related to save-excursion
primitive and buffer internals. Just like buffer text for the basic editing
primitives.

2) Lisp_XXX things are designed to be managed by GC, and other use of them
is suspicious and discouraged (embedding Lisp_Markers into struct excursion
is the poor solution in the absence of better alternatives). But, the
main purpose of this design is to avoid any dependency from GC to achieve
the lowest possible overhead of save-excursion.

Dmitry

excursion_3.patch
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